Commit 5a87b7a5 authored by Theodore Ts'o's avatar Theodore Ts'o
Browse files

ext4: call mpage_da_submit_io() from mpage_da_map_blocks() 



Eventually we need to completely reorganize the ext4 writepage
callpath, but for now, we simplify things a little by calling
mpage_da_submit_io() from mpage_da_map_blocks(), since all of the
places where we call mpage_da_map_blocks() it is followed up by a call
to mpage_da_submit_io().

We're also a wee bit better with respect to error handling, but there
are still a number of issues where it's not clear what the right thing
is to do with ext4 functions deep in the writeback codepath fails.

Signed-off-by: default avatar"Theodore Ts'o" <tytso@mit.edu>
parent 16828088

fs/ext4/inode.c

+33 −33
Original line number Diff line number Diff line
@@ -60,6 +60,7 @@ static inline int ext4_begin_ordered_truncate(struct inode *inode, 
}



static void ext4_invalidatepage(struct page *page, unsigned long offset);

static int ext4_writepage(struct page *page, struct writeback_control *wbc);



/*

 * Test whether an inode is a fast symlink.
@@ -2033,7 +2034,7 @@ static int mpage_da_submit_io(struct mpage_da_data *mpd) 
			BUG_ON(PageWriteback(page));



			pages_skipped = mpd->wbc->pages_skipped;

			err = mapping->a_ops->writepage(page, mpd->wbc);

			err = ext4_writepage(page, mpd->wbc);

			if (!err && (pages_skipped == mpd->wbc->pages_skipped))

				/*

				 * have successfully written the page
@@ -2189,14 +2190,15 @@ static void ext4_print_free_blocks(struct inode *inode) 
}



/*

 * mpage_da_map_blocks - go through given space

 * mpage_da_map_and_submit - go through given space, map them

 *       if necessary, and then submit them for I/O

 *

 * @mpd - bh describing space

 *

 * The function skips space we know is already mapped to disk blocks.

 *

 */

static int mpage_da_map_blocks(struct mpage_da_data *mpd)

static void mpage_da_map_and_submit(struct mpage_da_data *mpd)

{

	int err, blks, get_blocks_flags;

	struct ext4_map_blocks map;
@@ -2206,18 +2208,14 @@ static int mpage_da_map_blocks(struct mpage_da_data *mpd) 
	handle_t *handle = NULL;



	/*

	 * We consider only non-mapped and non-allocated blocks

	 * If the blocks are mapped already, or we couldn't accumulate

	 * any blocks, then proceed immediately to the submission stage.

	 */

	if ((mpd->b_state  & (1 << BH_Mapped)) &&

	if ((mpd->b_size == 0) ||

	    ((mpd->b_state  & (1 << BH_Mapped)) &&

	     !(mpd->b_state & (1 << BH_Delay)) &&

		!(mpd->b_state & (1 << BH_Unwritten)))

		return 0;



	/*

	 * If we didn't accumulate anything to write simply return

	 */

	if (!mpd->b_size)

		return 0;

	     !(mpd->b_state & (1 << BH_Unwritten))))

		goto submit_io;



	handle = ext4_journal_current_handle();

	BUG_ON(!handle);
@@ -2254,17 +2252,18 @@ static int mpage_da_map_blocks(struct mpage_da_data *mpd) 


		err = blks;

		/*

		 * If get block returns with error we simply

		 * return. Later writepage will redirty the page and

		 * writepages will find the dirty page again

		 * If get block returns EAGAIN or ENOSPC and there

		 * appears to be free blocks we will call

		 * ext4_writepage() for all of the pages which will

		 * just redirty the pages.

		 */

		if (err == -EAGAIN)

			return 0;

			goto submit_io;



		if (err == -ENOSPC &&

		    ext4_count_free_blocks(sb)) {

			mpd->retval = err;

			return 0;

			goto submit_io;

		}



		/*
@@ -2289,7 +2288,7 @@ static int mpage_da_map_blocks(struct mpage_da_data *mpd) 
		/* invalidate all the pages */

		ext4_da_block_invalidatepages(mpd, next,

				mpd->b_size >> mpd->inode->i_blkbits);

		return err;

		return;

	}

	BUG_ON(blks == 0);
@@ -2312,7 +2311,8 @@ static int mpage_da_map_blocks(struct mpage_da_data *mpd) 
	if (ext4_should_order_data(mpd->inode)) {

		err = ext4_jbd2_file_inode(handle, mpd->inode);

		if (err)

			return err;

			/* This only happens if the journal is aborted */

			return;

	}



	/*
@@ -2323,10 +2323,16 @@ static int mpage_da_map_blocks(struct mpage_da_data *mpd) 
		disksize = i_size_read(mpd->inode);

	if (disksize > EXT4_I(mpd->inode)->i_disksize) {

		ext4_update_i_disksize(mpd->inode, disksize);

		return ext4_mark_inode_dirty(handle, mpd->inode);

		err = ext4_mark_inode_dirty(handle, mpd->inode);

		if (err)

			ext4_error(mpd->inode->i_sb,

				   "Failed to mark inode %lu dirty",

				   mpd->inode->i_ino);

	}



	return 0;

submit_io:

	mpage_da_submit_io(mpd);

	mpd->io_done = 1;

}



#define BH_FLAGS ((1 << BH_Uptodate) | (1 << BH_Mapped) | \
@@ -2403,9 +2409,7 @@ flush_it: 
	 * We couldn't merge the block to our extent, so we

	 * need to flush current  extent and start new one

	 */

	if (mpage_da_map_blocks(mpd) == 0)

		mpage_da_submit_io(mpd);

	mpd->io_done = 1;

	mpage_da_map_and_submit(mpd);

	return;

}
@@ -2437,15 +2441,13 @@ static int __mpage_da_writepage(struct page *page, 
	if (mpd->next_page != page->index) {

		/*

		 * Nope, we can't. So, we map non-allocated blocks

		 * and start IO on them using writepage()

		 * and start IO on them

		 */

		if (mpd->next_page != mpd->first_page) {

			if (mpage_da_map_blocks(mpd) == 0)

				mpage_da_submit_io(mpd);

			mpage_da_map_and_submit(mpd);

			/*

			 * skip rest of the page in the page_vec

			 */

			mpd->io_done = 1;

			redirty_page_for_writepage(wbc, page);

			unlock_page(page);

			return MPAGE_DA_EXTENT_TAIL;
@@ -3071,9 +3073,7 @@ retry: 
		 * them for I/O.

		 */

		if (!mpd.io_done && mpd.next_page != mpd.first_page) {

			if (mpage_da_map_blocks(&mpd) == 0)

				mpage_da_submit_io(&mpd);

			mpd.io_done = 1;

			mpage_da_map_and_submit(&mpd);

			ret = MPAGE_DA_EXTENT_TAIL;

		}

		trace_ext4_da_write_pages(inode, &mpd);

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